JPH0213363B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a thin film magnetic head, and more particularly to a method of manufacturing a thin film magnetic head with excellent electromagnetic conversion characteristics. The electromagnetic conversion characteristics of a thin film magnetic head are largely dependent on the magnetic properties of the magnetic core. Because thin-film magnetic heads are used in high-frequency regions, the magnetic core is given uniaxial magnetic anisotropy, the axis of easy magnetization is oriented in the track width direction, the axis of hard magnetization is set in the excitation direction, and magnetization reversal due to magnetization rotation is achieved. This method takes advantage of the high magnetic permeability in the high frequency range. It is known that a relatively high magnetic permeability can be obtained by a magnetic film having a small magnetostriction constant and a small induced uniaxial anisotropy constant. A Ni-Fe alloy film is known as such a magnetic film. It was discovered in Japanese Patent Laid-Open No. 1983-1997 that a magnetic film with a negative magnetostriction constant is desirable as the magnetic core of a thin-film magnetic head.
It is disclosed in Publication No. 101124. Japanese Unexamined Patent Publication 1973-
101124, the reason why a magnetic film with a negative magnetostriction constant is desirable for the magnetic core of a thin-film magnetic head is that tensile stress acts in the direction perpendicular to the track width direction of the magnetic core, and this tensile stress in the direction perpendicular to the track width direction It is stated that the purpose is to prevent rotation of the axis of easy magnetization due to According to the experiments conducted by the present inventors, it is clear that in addition to the tensile stress in the direction perpendicular to the track width direction, tensile stress also acts on the magnetic core of the thin film magnetic head, especially the upper magnetic core. It became.
Furthermore, it has become clear that compressive stress also acts in the track width direction of the magnetic core and in a direction perpendicular to the track width direction. It has also become clear that when the magnetostriction coefficient takes a large negative value, the magnetic permeability decreases in response to tensile stress. Therefore, as a magnetic core of a thin film magnetic head,
It was found that stable characteristics could not be obtained only by making the sign of the magnetostriction constant negative. An object of the present invention is to provide an improved method of manufacturing a thin film magnetic head that always exhibits stable electromagnetic conversion characteristics. In order to obtain stable electromagnetic conversion characteristics, the magnetostriction constant of at least the upper magnetic core among the upper magnetic core and the lower magnetic core constituting the magnetic core needs to be within 1×10 ⁻⁶ in absolute value. A method for manufacturing a thin film magnetic head of the present invention that achieves the above object comprises forming a lower magnetic core on an insulating substrate, forming a magnetic gap on the lower magnetic core,
A coil conductor is formed above the magnetic gap, an insulating film is formed between the coil conductors and on the coil conductor, and one end of the insulating film contacts one end of the lower magnetic core, and the other end contacts the lower magnetic core. forming an upper magnetic core that faces the other end of the magnetic core through a magnetic gap, at least the upper magnetic core is made of a Ni-Fe alloy whose composition is controlled by sputtering, and the upper magnetic core surface It is formed by controlling the crystal orientation so that there are many (111) planes or (100) planes in the plane parallel to the upper magnetic core, and is heat-treated after forming the upper magnetic core to have a magnetostriction constant of 1 × 10 ^-6 or less in absolute value. It is characterized by Hereinafter, the thin film magnetic head according to the present invention will be explained in detail with reference to the drawings. In FIG. 1, 1 is an insulating substrate, 2 is a base film formed on the insulating substrate 1, 3 is a lower magnetic core formed on the base film 2, 4 is laminated on the lower magnetic core 3, and one end is the lower magnetic core. It connects to one end of the core 3, and the other end connects to the other end of the lower magnetic core 3 with a predetermined magnetic gap G.
5 is a coil conductor arranged to penetrate between the lower magnetic core 3 and the upper magnetic core 4, 6 is between the coil conductors 5,
An insulator 7 filled between the coil conductor 5 and the lower magnetic core 3 and upper magnetic core 4 and between the magnetic gap G is a protective film covering the upper magnetic core 4 and the coil conductor 5. The upper magnetic core 4 has a magnetostriction constant within 1×10 ⁻⁶ in absolute value. The stress acting on the lower magnetic core 3 and the upper magnetic core 4 will be explained with reference to FIGS. 2 and 3. By patterning the lower magnetic core 3, tensile stress is applied in the direction indicated by the arrow in FIG. 2. That is, near the edges of the pattern, tensile stresses 21, 21', 2 are applied in the direction along the edges of the pattern.
1'' and 21 act on the upper magnetic core 4. The upper magnetic core 4 is more complicated than the lower magnetic core 3. The following three types of stress act on the upper magnetic core 4. Stress σ _a generated by patterning as in 3
22, 22', 22'', 22, (2) Tensile stress σ _b generated by forming a magnetic film on the riding part near the front gap G and back gap 23, 23', (3) Upper magnetic core 4 Stress σ _c 2 exerted on the upper magnetic core 4 by the protective film 7 formed thereon
There are three types: 4, 24', 24'', 24, 24'''''. The stress σ _b generated by forming the magnetic film on the run-on part 23, 23' is in the direction parallel to the run-on edge. In other _words , tensile stress in the track width direction acts. It varies depending on the conditions for forming the aluminum oxide film (7). In the case of the aluminum oxide film formed by sputtering performed by the inventors, compressive stress acts in the direction along the edge of the pattern of the upper magnetic core, and compressive stress acts in the direction along the edge of the run-up.
In other words, the stress σ _c exerted by the protective film on the upper magnetic core
24, 24', 24'', 24, 24''''' are stress σ _a 22, 2 generated by patterning.
2′, 22″, 22 and the stress generated by forming a magnetic film on the riding part σ _b 23,2
The relationships between 3', tensile stress, and compressive stress are reversed. In this way, complex stress acts on the upper magnetic core. Next, magnetic permeability when stress is acting on the uniaxial magnetic anisotropic film will be explained. When stress acts on the hard axis of magnetization of a uniaxial magnetically anisotropic film with magnetostriction constant λ,
When the magnetic permeability when no stress is applied is 2000, the relationship between the magnetostriction constant, stress, and magnetic permeability is shown in Figure 4. The numbers in FIG. 4 represent magnetic permeability. When the magnetostriction constant is positive, magnetic permeability decreases if compressive stress is applied in the direction of the hard magnetization axis, and magnetic permeability increases if tensile stress within the limit curve 30 is applied to the hard magnetization axis. If a tensile stress larger than the limit curve 30 is applied, rotation of the axis of easy magnetization occurs, resulting in excitation in the direction of the axis of easy magnetization,
Magnetization reversal occurs due to domain wall movement, and the magnetic permeability in the high frequency region decreases significantly, deteriorating the electromagnetic conversion characteristics of the thin film magnetic head. When the magnetostriction constant is negative, magnetic permeability decreases when tensile stress is applied to the hard magnetization axis, and magnetic permeability increases when compressive stress within the limit curve 31 is applied to the hard magnetization axis. limit curve 31
If a larger compressive stress is applied, the axis of easy magnetization will rotate, and the magnetic permeability in the high frequency region will decrease significantly. For a magnetic film with a large magnetostriction constant λ, the magnetic permeability changes when a small stress in the direction of the hard magnetization axis acts. A thin film magnetic head consisting of a magnetic core with a large absolute value of the magnetostriction constant has large variations in read voltage and undesirable overwriting characteristics. The upper magnetic core of the thin-film magnetic head has stress σ a generated by patterning as described above, stress σ _b generated by forming the magnetic film on the run-on portion, _and stress exerted on the upper magnetic core by the protective film. There is a stress σ _c . According to the experiments of the present inventors,
These stresses varied depending on the conditions for forming the magnetic film, the shape of the pattern, the shape of the overlapping portion, the conditions for forming the protective film, etc., but were approximately within ±10 ⁸ N/m ² . Therefore, as shown in FIG. 4, in order to maintain good and stable electromagnetic conversion characteristics of the thin film magnetic head, it is necessary to keep the absolute value of the magnetostriction constant of the magnetic core within 1×10 ^-6 . ^Ni -Fe
The case of a alloy film will be explained. Ni-Fe alloy films are often used for the magnetic core of thin-film magnetic heads. Ni-Fe alloy films used in thin-film magnetic heads are often polycrystalline. As with a single crystal film, the degree of crystal orientation is important for the magnetostriction constant of a polycrystalline film. In a Ni-Fe alloy film, if there are many (111) planes on the plane parallel to the film surface, the magnetostriction constant becomes zero at approximately 80.2% Ni by weight, and the (100) plane on the plane parallel to the film surface
When there are many surfaces, the magnetostriction constant becomes zero at approximately 81.7% by weight Ni. That is, in order to keep the absolute value of the magnetostriction constant within 1×10 ⁻⁶ in a Ni—Fe alloy film, it is important to control not only the composition of the film but also the degree of orientation of the film. Figure 5 shows the change in magnetic permeability when stress is applied to the hard axis of magnetization of a (100) oriented Ni-Fe alloy film. The magnetostriction constants of films a, b, c, and d in Figure 5 were +4.6×10 ^-6 , +1.1×10 ^-6 , -0.1×10 ^-6 and -0.8×10 ^-6 respectively. . Ni with large magnetostriction constant
-Fe-based alloy films have a large change in magnetic permeability with small stress. In particular, film a with a large magnetostriction constant of +4.6×10 ^-6
The rotation of the axis of easy magnetization occurs under large tensile stress, and the magnetic permeability decreases significantly. Example An Al ₂ O ₃ --TiC ceramic substrate was used as the insulating substrate 1. As a substrate, within Al ₂ O ₃ −TiC
SiC, Zn ferrite, Ni−Zn ferrite, Mn−
Other ceramic substrates such as Zn ferrite and Al ₂ O ₃ -TiC may also be used. Next, a sputtered Al ₂ O ₃ film was formed as a base film 2 on the substrate 1 . The base film is not limited to Al ₂ O ₃ , but other materials may be used as long as they are oxides or fluorides that have good electrical insulation and do not substantially cause problems in reaction with the Ni-Fe alloy film. Next, a Ni-Fe alloy as the lower magnetic core 3 was formed by sputtering. Here, a film in which the magnetostriction constant of the Ni-Fe film was approximately zero, a film in which the magnetostriction constant was 2×10 ⁻⁶ , and a film in which the magnetostriction constant was −2×10 ⁻⁶ were fabricated. The magnetostriction constant of a film varies not only with the film composition but also with the degree of crystal orientation of the film, so not only the film formation conditions but also the heat treatment after film formation are important. Next, the magnetic gap G
Al ₂ O ₃ constituting the structure was formed by a sputtering method. As the insulator of the coil conductor 5, a polyimide resin having good heat resistance was used. Coil conductor 5 is made of Cu, which has excellent electron migration characteristics. Although Cu is formed by a sputtering method, it may also be formed by a vacuum evaporation method or a plating method. Then the second
Polyimide resin was used as the insulating film. The upper magnetic core 4, like the lower magnetic core 3, was formed from a Ni--Fe alloy by sputtering. Here, a film with a magnetostriction constant of almost zero, a film with a magnetostriction constant of 2×10 ^-6 and a film with a magnetostriction constant of -2×10 ^-6 were fabricated. Ion milling was used to pattern the lower magnetic core 3, magnetic gap G, insulating film, coil conductor 5, second insulating film, and upper magnetic core 4. In addition to the ion milling method, a sputter etching method or a chemical etching method may be used as the patterning method. Next, a terminal portion was formed by plating, and a protective film 7 of Al ₂ O ₃ was formed by sputtering. Next, the surface facing the recording medium, which serves as the air bearing surface, was machined to test the electromagnetic conversion characteristics of the thin-film magnetic head. The recording medium used in the test was γ-Fe ₂ O ₃ magnetic powder. The peripheral speed is 40 m/s, and the floating spacing between the magnetic head and recording medium is
Tested at 0.35 μm. The electromagnetic conversion characteristics of the thin film magnetic head with magnetic cores having different magnetostriction constants are shown in Table 1.

[Table] As is clear from this table, the thin film magnetic head consisting of a magnetic core with a small absolute value of magnetostriction constant exhibited good electromagnetic conversion characteristics. As described above, stress inevitably acts on the magnetic core due to the structure and manufacturing process of the thin film magnetic head, but according to the manufacturing method of the present invention, a magnetic film with a small absolute value of the magnetostriction constant is used as the magnetic core. It is possible to provide a thin film magnetic head that can be manufactured and has high magnetic permeability even under stress. Further, the method for manufacturing a thin film magnetic head of the present invention has the advantage that a thin film magnetic head with good electromagnetic conversion characteristics and less variation can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the thin-film magnetic head of the present invention, FIG. 2 is a perspective view showing how stress is generated in the lower magnetic core, and FIG. 3 is a perspective view showing how stress is generated in the upper magnetic core. , FIG. 4 is a characteristic curve diagram showing changes in magnetic permeability due to stress, and FIG. 5 is a characteristic curve diagram showing the relationship between hard axis stress and relative magnetic permeability using the magnetostriction constant as a parameter. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... Base film, 3... Lower magnetic core, 4... Upper magnetic core, G... Magnetic gap, 5...
Coil, 6...insulator, 7...protective film.

Claims (1)

[Claims] 1. A lower magnetic core is formed on an insulating substrate, a magnetic gap is formed on the lower magnetic core, a coil conductor is formed above the magnetic gap, and a coil conductor is formed between the coil conductors and the coil. Forming an insulating film on the conductor,
A method for manufacturing a thin film magnetic head, comprising forming an upper magnetic core on the insulating film, one end of which is in contact with one end of the lower magnetic core, and the other end of which is opposed to the other end of the lower magnetic core via a magnetic gap. , at least the upper magnetic core is made of a Ni-Fe alloy whose composition is controlled by a sputtering method, and the crystal orientation is such that there are many (111) planes or (100) planes parallel to the upper magnetic core surface. 1. A method for manufacturing a thin film magnetic head, characterized in that the upper magnetic core is formed under controlled conditions, and is heat treated after forming the upper magnetic core, so that the absolute value of the magnetostriction constant is 1×10 ^-6 or less.